Liquid crystal display device has been disseminated as a space-saving image display device with low power consumption, and has been expanding its applications year by year.
The liquid crystal display device is generally configured by providing polarizing plates on both sides of a liquid crystal cell. The polarizing plate functionally allows only light having a certain directionality of plane of polarization to pass therethrough, and performance of the polarizing plate largely affects performance of the liquid crystal display device. The polarizing plate is generally configured by a polarizer which is typically composed of an oriented polyvinyl alcohol film having iodine or dye adhered thereto, and translucent protective films bonded to the front and back surfaces of the polarizer.
With recent expanding applications of the liquid crystal display device, there has been an increasing trend of large-sized and high-definition applications such as television set, and this has further pushed up a level of required quality of the polarizing plate. In particular, large-sized and high-definition liquid crystal display devices have increasingly been used outdoors and under various severe environments than before. From this point of view, in recent years, the polarizing plate used for the liquid crystal display device has been strongly demanded to improve the durability of the polarizer under high-temperature and high-humidity conditions.
Meanwhile, there have been known several methods of improving the durability of the polarizer, by controlling pH to acidify a layer provided between the polarizer protecting film and the polarizer. For example, JP-A-2003-165188 discloses a method of providing, between the polarizer protecting film and the polarizer, a layer which contains a polyester resin having a dissociative organic acid group, and JP-A-2004-12578 discloses a method of adding a hydroxycarboxylic acid-based compound having a substituent with a small number of carbon atoms, to the adhesive layer. JP-A-H06-265725 discloses a method of adding an antioxidant selected from phenolic compound, phosphorus-containing compound and sulfur-containing compound, to the adhesive layer.
On the other hand, JP-A-2011-118135 discloses addition of barbituric acid to the protective film.